The present invention relates to a technology effective for application to a mounting technology for implementing a semiconductor chip on a wiring board with an adhesive obtained by mixing a large number of conductive particles into an insulative resin interposed therebetween.
As a mounting technology for implementing a semiconductor chip on a printed circuit board or a wiring board by a face down bonding system, a mounting technology (hereinafter called xe2x80x9cbumpless mounting technologyxe2x80x9d) has been developed which eliminates for the need of conductive bumps and makes use of an anisotropic conductive resin (e.g., ACF: Anisotropic Conductive Film) obtained by mixing a large number of conductive particles into an insulative resin. Since the semiconductor chip is contact-bonded to the wiring board with the anisotropic conductive resin interposed therebetween to thereby make it possible to bond and fix the semiconductor chip to the wiring board and electrically connect both by conductive particles interposed between wires on the wiring board and electrode pads (bonding pads) on the semiconductor chip, the present bumpless mounting technology allows the production of a semiconductor device and an electronic device both reduced in thickness and low in cost as compared with a flip chip mounting technology using bumps.
Incidentally, the bumpless mounting technology has been described in, for example, Japanese Published Unexamined Patent Application No. Hei 8-115949.
However, the bumpless mounting technology brings about the following problems.
The semiconductor chip principally comprises a semiconductor substrate, a multilayer wiring layer obtained by stacking an insulating layer and a wiring layer on a circuit forming surface of the semiconductor substrate in plural stages, and protective films (final protective films) formed so as to cover the multilayer wiring layer. The electrode pads of the semiconductor chip are formed on a wiring layer corresponding to the top layer in the multilayer wiring layer and exposed from bonding openings defined in the protective films. Namely, since the electrode pads of the semiconductor chip are provided at position below the protective films, the conductive particles are sandwiched between the wires on the wiring board and the protective films on the semiconductor chip when the conductive particles are interposed between the wires of the wiring board and the electrode pads of the semiconductor chip to obtain continuity between the two.
On the other hand, since the protective films of the semiconductor chip are normally formed of an insulating film such as a silicon oxide film, a silicon nitride film or the like to prevent the entry of impurities such as Na ions, etc. and moisture, these insulating films are hard and brittle. Therefore, cracks are developed in the protective films of the semiconductor chip with portions between which the conductive particles are interposed, as the starting points. Since the impurities such as the Na ions, and the moisture are easy to enter inside the protective films when the cracks occur in the protective films of the semiconductor chip, the semiconductor device and the electronic device are reduced in reliability.
An object of the present invention is to provide a technology which allows conductive particles to prevent cracks developed in protective films on a semiconductor chip.
Another object of the present invention is to achieve the above object and provide a semiconductor device and an electronic device each of which has a high degree of reliability and is thinned and low in cost.
The above, other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
Summaries of typical ones of the inventions disclosed in the present application will be described in brief as follows:
(1) There is provided a semiconductor device comprising a semiconductor chip including, over one main surface thereof, first wires, protective films formed so as to cover other portions excluding parts of the first wires, flexible layers respectively formed on the protective films so as to exclude the parts of the first wires, and second wires having first portions respectively electrically connected to the parts of the first wires, and second portions respectively drawn onto the flexible layers; a wiring board having third wires over one main surface thereof; and an adhesive comprising a large number of conductive particles contained in an insulative resin, and wherein the semiconductor chip is bonded to the wiring board with the adhesive interposed therebetween in a state in which the one main surface thereof is face to face with the one main surface of the wiring board, and the second portions of the second wires are respectively electrically connected to the third wires with some of the large number of conductive particles interposed therebetween.
(2) There is also provided a semiconductor device, comprising a semiconductor chip including, over one main surface thereof, first wires, and protective films formed so as to cover other portions excluding parts of the first wires; a wiring board including, over one main surface thereof, second wires, flexible layers formed so as to cover other portions excluding parts of the second wires, and third wires having first portions respectively electrically connected to the parts of the second wires, and second portions respectively drawn onto the flexible layers; and an adhesive comprising a large number of conductive particles contained in an insulative substance, and wherein the semiconductor chip is bonded to the wiring board with the adhesive interposed therebetween in a state in which the one main surface thereof is face to face with the one main surface of the wiring board, and the parts of the first wires are respectively electrically connected to the second portions of the third wires with some of the large number of conductive particles interposed therebetween.
(3) There is further provided an electronic device comprising a semiconductor chip including, over one main surface thereof, first wires, protective films formed so as to cover other portions excluding parts of the first wires, flexible layers respectively formed on the protective films so as to exclude the parts of the first wires, and second wires having first portions respectively electrically connected to the parts of the first wires, and second portions respectively drawn onto the flexible layers; a wiring board having third wires over one main surface thereof; and an adhesive comprising a large number of conductive particles contained in an insulative resin, and wherein the semiconductor chip is bonded to the wiring board with the adhesive interposed therebetween in a state in which the one main surface thereof is face to face with the one main surface of the wiring board, and the second portions of the second wires are respectively electrically connected to the third wires with some of the large number of conductive particles interposed therebetween.
(4) There is still further provided an electronic device comprising a semiconductor chip including, over one main surface thereof, first wires, and protective films formed so as to cover other portions excluding parts of the first wires; a wiring board including, over one main surface thereof, second wires, flexible layers formed so as to cover other portions excluding parts of the second wires, and third wires having first portions respectively electrically connected to the parts of the second wires, and second portions respectively drawn onto the flexible layers; and an adhesive comprising a large number of conductive particles contained in an insulating resin, and wherein the semiconductor chip is bonded to the wiring board with the adhesive interposed therebetween in a state in which the one main surface thereof is face to face with the one main surface of the wiring board, and the parts of the first wires are respectively electrically connected to the second portions of the third wires with some of the large number of conductive particles interposed therebetween.